Date: March 8, 2004
Robert Packard Center News Network

Most ALS scientists dream that what causes the disease would turn out
to be something dramatic that they'd just overlooked: an odd, neurotoxic
chemical that comes from exposure to pesticides after eating walnuts,
for example.

But researchers at The Packard Center are realizing that finding the
disease's cause-and the cure-will instead depend on small, quiet
detective work at the molecular level. Recently, Center scientist Val
Culotta has made a discovery typical of that approach. While it won't
make the front page of major dailies, it's an important find because it
further clarifies the biology of a process that goes awry in ALS. Not
only does her work save her fellow scientists months of research time,
but it also suggests more finely-targeted studies to reveal what goes
wrong.

And when you've got 24 investigators pooling such discoveries, that
whittles the problem down.

Val Culotta, like other ALS researchers, is aware that in both the
common, sporadic form of ALS and the familial sort, patients' motor
neurons show an unnatural clumping of abnormally-structured protein. The
clumps can be made up of a protein, SOD1. "Scientists generally agree
that this clumping, or aggregation, might play havoc with motor neurons.
It could trigger the symptoms of the disease and cell death," says
Culotta. But how?

How, she asks, do you cause the protein misfolding that leads to
aggregates?

From her studies of SOD1, which is an enzyme, Culotta well understands
its structure and behavior. She typically observes SOD1 within the
confines of single-celled yeasts, her test laboratory. Culotta studies
both natural yeast SOD1 and human SOD1 that yeasts have been prodded
into manufacturing.

In order to function normally, SOD1 requires zinc and copper, she says.
Recently, Culotta has focused on the enzyme's relation to the latter
metal. How does SOD1 get its copper? Typically, the metal, which doesn't
float around randomly in cells, is instead captured by a "chaperone"
molecule which efficiently hands it over to the enzyme.

For some time, scientists thought ALS might be caused by a malfunction
in the chaperones and their delivery of copper. But Packard Center
researcher Phil Wong and colleagues showed that ALS model mice
engineered to be without the chaperones still came down with motor
neuron disease.

"It was elegant work," says Culotta. "But it also raised another
question."

Even though Wong's test mice lacked copper chaperones and even though
those molecules were needed to "complete" SOD1 enzymes, the researchers
saw that the mouse cells still had a fair amount of complete, active
SOD1. Culotta reasoned there must be another way, a non-chaperone way,
to deliver copper to the enzyme.

So she tried every other molecule she could think of with a role in
supplying copper in a living cell. Finally, Culotta found two molecules:
glutathione and the enzyme, glutathione reductase. "When we eliminated
those two molecules in cells, the activity of SOD1 enzymes dropped
dramatically," she says. That showed they're very likely part of an
alternate route animal cells use to supply copper. "Finding that," she
says, "took an enormous amount of time."

But Culotta's study has led to an interesting find. In cultures of
cells that lack copper chaperones but which, instead, seem to rely upon
the glutathione molecules for their copper, those cells have far less
SOD1. "It's very preliminary," she says, "but there's a suggestion that
these alternate routes may be highly damaging to SOD1. Damage could lead
to aggregation." Culotta hopes to begin studies soon to see how this
fits into the ALS process.

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About the Robert Packard Center for ALS Research at Johns Hopkins

Located in Baltimore, the Robert Packard Center for ALS Research at
Johns Hopkins is a collaboration of scientists worldwide, working
aggressively to develop new treatments and a cure for amyotrophic
lateral sclerosis (ALS), also known as Lou Gehrig's disease. The Center
is the only institution of its kind dedicated solely to the disease. Its
research is meant to translate from the laboratory bench to the clinic
in record time.

Scientists and clinician members of the Center are unsurpassed at
moving drugs reliably and rapidly from preclinical experiments to human
trials. They're linked, directly or indirectly, to the world's major
pharmaceutical and biotechnology companies, which have both
infrastructure and experience to make promising drugs into therapies.

Center scientists are the first to propose and test a combination
approach to drug therapy, a tactic that has worked for AIDS, cancer and
other diseases.

ALS is a devastating, progressive neuromuscular disease that causes
complete paralysis and loss of function - including the ability to eat,
speak and breathe. ALS progresses quickly and is not curable. Most
patients die within five years of diagnosis.

To learn more about The Robert Packard Center for ALS Research at Johns
Hopkins, including information on its latest research and treatment, log
on to www.alscenter.org